Field of the Invention
The present invention relates to lubricants and, more particularly, to lubricating compositions especially adapted for use in conjunction with projectiles and firearms and methods of compounding such lubricants.
One of the more important problems with unjacketed bullets is known as "leading", which is the phenomenon of lead from the bullet being deposited, by melting or otherwise, on the interior surfaces of the gun barrel. When this occurs, it is difficult to fire the bullets accurately and consistently even with exactly matched loads in a firearm even from a fixed position. In an attempt to overcome the detrimental effects of leading, commercial ammunition manufacturers and individual hand loaders have adopted various expedients. One of these consists of jacketing the lead bullet with gilding metal, a copper base alloy nominally containing 5 percent zinc. Unfortunately, while the jacketed bullet is a significant advance in the art, it too has disadvantages, the more important of which include the expensiveness and "copper fouling"; i.e., the transference of copper from the bullet to the inner surface of the barrel. Recently aluminum jacketed bullets have been introduced for pistol and revolvers to solve the leading problem at reduced cost and yet allow suitable upset upon impact. Yet, this round is not suitable for rifles where bullet velocities are high enough to cause aluminum fouling.
It becomes apparent that the foregoing improvements have not been complete answers to all of the problems betsetting the marksman. Indeed, the proposed solutions to many of the problems have not only frequently raised difficult new problems but also have served to emphasize the problems remaining unsolved. For example, friction was once considered to be such a small factor of ballistics that it was often ignored. Now, the opposite is true particularly since it is known that even a relatively low velocity can create sufficient frictional heat to actually melt the surface of a lead bullet and cause leading in the barrel and lead gases can be produced. Furthermore, gun barrel imperfections even though microscopic in size can cause small particles of metal jackets, zinc bases or lead to become embedded in the surface of the barrel. Continued firing only creates additional deposits which can shift positions within the barrels resulting in erratic trajectories.
Efforts to counteract frictional forces with most prior art wax lubricants have not been too successful particularly where the lubricant selected is a candle wax or one that has been employed to combat frictional effects in a non-ballistics application. A probable reason for the failure of such a wax lubricant may be traceable to the sometimes severe condrtions encountered in shooting a firearm where bullet velocities may be as high as 3,000 or 4,000 feet per second and where pressures on the bullet may be as high as 50,000 pounds per square inch. In addition, many of the prior art wax lubricants, including those intended for ballistics applications, are unstable at the frictional temperatures and pressures encountered by a bullet rapidly traveling through a gun barrel. Furthermore, the prior art greased wax compounds are tacky and thus tend to pick up grit and sand particles which can contribute to, rather than inhibit, barrel wear. Some of the other prior art wax lubricants suffer from the disadvantage of being too costly or too difficult to apply to either the firearm or the ammunition.
The whole broad problem of providing a suitable wax lubricant for ballistics applications is rendered even more difficult by the necessity that the lubricant possess a formidable array of anomalous characteristics. For example, it should be noncorrosive to both surfaces it is to lubricate. It should remain stable over the entire temperature range encountered in ballistic applications. It should be fairly inexpensive. It should have the capacity to tenaciously fill any pores in the barrel and yet provide a fairly smooth surface.
In addition to the ballistic considerations above there are production considerations. As noted above, it is a common practice in loading bullets into shell cases to coat each bullet, prior to loading, with a lubricant to reduce the "leading effect" of the bullet on the bore of the firearm through which the bullet is projected. The most commonly used lubricant is beeswax which presents a problem in that residue of the beeswax slowly builds up on the loading mechanism of automatic equipment used to load the bullets into the shell cases. This residue eventually clogs the mechanism for the purpose of disassembling the loading equipment for cleaning. It has remained a problem to find suitable compositions for cleaning. It has remained a problem to find suitable composition for coating bullets without at the same time creating problems in use of automated loading equipment.
In addition to the above concerns there is the more recent recognition that improperly ventilated indoor ranges can develop sufficient levels of lead gases under intensive shooting conditions to be a possible health hazard unless the bullets are coated or jacketed.
Yet, those precise ranges have a maximum need for inexpensive target ammunition so any such coating or jacket should be cheap to make so that ranges can shoot a maximum number of rounds within a given ammunition budget without health hazards.